Electric device for the treatment of a gaseous fluid

ABSTRACT

An electric device for the ionization treatment of a gaseous fluid. The device comprises a generator of unidirectional pulses of electric current which are fed to a treatment element disposed in the gaseous fluid to be treated. In order to increase the number of negative ions the treatment element comprises a first electrode, which is connected to the generator of unidirectional current pulses. At least one of the faces of this first electrode is covered by a solid dielectric material which in turn is completely covered on the side of the treatment space by a gridlike second electrode, which is connected to a reference potential source, such as earth.

United tates Patent Guerin 1 1 Aug. 5, 1975 [54] ELECTRIC DEVICE FOR THE TREATMENT 2,440,455 4/1948 White 55/139 OF A GASEOUS FLUID 2,575,664 11/1951 James. 250/535 2,639,781 5/1953 Savitz... 55/139 X Inventor: Robert rin. Puteaux, France 2,726,731 12/1955 Brixius... 55/138 3 [731 Assignees: Georges rew Aime Pramaggiore 5132313; 11133; $111,251.18; 221133? both of vllelulfr France 3,417,302 12/1968 Lueder 317 262 A13 [22] Filed. July 3 973 3,438,136 4/1969 Raymond... 34/72 3,567,620 3/1971 Ingram 250/53" [21] Appl. No.: 376,162

FOREIGN PATENTS OR APPLICATIONS 17,885 1903 United Kingdom 250/532 [301 Forelg" PP Pnomy Data 6,105 1908 United Kingdom 250/532 July 26, 1972 France 72.26934 Primary E.\aminer-Bernard Nozick [52] [1.5. CI. 250/535; 55/139; 55/152; Attorney, Agent, or Davis Miller &

317/4 Mosher [51] Int. Cl ClOg 21/02 [58] Field of Search 250/531, 532, 533, 534,

250/535, 536, 537, 538. 539, 540, 541, 542, [57] ABSTRACT 543, 544, 545, 546, 547; 55/2, 123, 139, An electric device for the ionization treatment of a 150, 151, 152 154 155 146, 101; 317/262 gaseous fluid. The device comprises a generator of AE, 4 unidirectional pulses of electric current which are fed to a treatment element disposed in the gaseous fluid to [56] References Cit d be treated. In order to increase the number of nega- UNITED STATES PATENTS tive ions the treatment element comprises a first elec- 871,652 11/1907 Ward 313/309 x tf Whlch i i f fi f: i i f 1,284,042 11/1918 1361811116 317/262 AE P "1 9 L 1,396,222 11/1921 Lindemmm h I 250/532 first electrode 1s covered by a solid d1electr1c material L725661 8/1929 Mcpanlund h I 250/533 which in turn is completely covered on the side of the 2 0 3 2 93 yaglou H 250 53 X treatment space by a grid-like second electrode, which 2,049,561 8/1936 Grave 55/139 X is connected to a reference potential source. such as 2,085,735 7/1937 Brion et a1. 55/150 X earth, 2,085,758 7/1937 Krutzsch 1 1 1 55/2 2,290,376 7/1942 Marshall 98/211 x 15 Claims, 3 Drawing Figures PATENTEU AUG 5 SHEET HON PATENTEU AUG 51975 SHEET ELECTRIC DEVICE FOR THE TREATMENT OF A GASEOUS FLUID The present invention relates to an electrical device for the treatment of a gaseous fluid, of the type comprising an electric generator and two electrodes, each electrode being connected to one of the poles of the generator. A particular, but not exclusive application of the present invention is in the treatment of air containing pollutant molecules such as S H S, NI-I CH or of the type C H by setting up a zone with different electric potentials in a so-called treatment space, where the gaseous fluid to be treated circulates.

In known devices of this type, the treatment space is simultaneously directly in contact with both the electrodes, so that these known devices do not make it possible to increase the content of negative ions present in the gaseous fluid to be treated. Moreover, in the case where these known devices are used to remove smells from, and to purify, the atmosphere, they have a tendency to oxidize the nitrogen in the air, which leads to the production of substances which are dangerous to living beings, such as nitrous and nitric acids.

According to the present invention there is provided an electric device for the treatment of a gaseous fluid by the setting up of a zone with different electric potentials in a treatment space, comprising at least one treatment element to be disposed in the gaseous fluid to be treated, the treatment element comprising a first electrode which in use of the device is to be connected to a source of positive unidirectional pulses of electric current, a solid dielectric material so disposed about the first electrode as to insulate electrically at least one face of the first electrode from the gaseous fluid to be treated, and a second, grid-like, electrode disposed so as to cover at least partially the dielectric material on the side to be exposed to the gaseous fluid to be treated.

Thus, in the device made in accordance with the present invention, the gaseous fluid to be treated is no longer in direct contact with the positive or first electrode so that the negative ions produced in the electrical discharges generated by this device are no longer removed by the first electrode and hence there is an increase in the number of negative ions present.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 represents the circuit diagram of a first embodiment of the device made in accordance with the present invention;

FIG. 2 represents the circuit diagram of a second embodiment of the device made in accordance with the present invention; and

FIG. 3 represents a cross-section through an embodiment of a treatment element of the device made in accordance with the invention.

FIG. 1 represents an embodiment of an electric device for the treatment of gaseous fluid made in accordance with the invention, which device comprises an electric generator 1, an electrode in the form of a continuous plate 2, the so-called back electrode, and two electrodes in the form of grids or meshes, made of stainless steel, 3 and 4, the so-called front electrodes. The generator 1 is of the type which provides unidirectional pulses of current (or a unidirectional pulsed current). The back electrode or plate 2 is connected to the positive terminal HT of the generator 1, while the front electrodes or grids 3 and 4 are connected to the other, neutral terminal of the generator 1. In the illustrated embodiment the neutral terminal is connected to earth.

The plate 2 is insulated electrically from the gaseous fluid to be treated which circulates in zones of a treatment space 20, by insulating plates or layers 5 which are represented schematically in FIG. 1. Each dielectric insulating plate or layer 5 covers one of the faces of the plate 2 and is interposed between the plate 2 and the corresponding grid 3 or 4 which completely covers the insulating plate or layer 5 on the side of the corresponding zone of the treatment space 20. As can be seen in the drawings, the plate 2 is surrounded by the treatment space 20 and is covered on each of its two faces by the corresponding insulating plate or layer 5, which is itself covered by the corresponding grid 3 or 4, the grids 3 and 4 being connected electrically to one another by a conductor in such a way as to be brought to the same electric potential.

Advantageously, the plate 2 is equipped with projections or raised parts 2a which are uniformly distributed over the entire area of each of its faces. Each of the projections 2a act as a point of emission of positive polarity of an intense electric induction field giving rise within the treatment space 20 to a spike of discharges. Due to the uniform distribution of the projections 2a, the positive spikes coming from the combination formed by the plate 2 covered by the insulating plates or layers 5, are uniformly distributed over the entire area of the combination, so that the distribution of the energy set up in these spikes is substantially uniform.

Advantageously, as FIG. 3 shows, each projection 20 of one face of the plate 2 coincides with a hole 30 or 4a of the corresponding grid 3 or 4.

Each insulating plate or layer 5 comprises substantially pin-point zones or zones of small area 5a, that is to say zones, the average diameter of which is substantially equal to or less than that of the holes 3a and 4a of the corresponding grid 3 and 4, these zones having a higher dielectric constant (in the case of FIGS. 1 and 2) or a lower thickness (in the case of FIG. 3) than that (dielectric constant or thickness, depending on the particular case) of the remainder of the insulating plate or layer. The zones 5a are uniformly distributed over the entire area of the plate or layer 5 and thus cause the electric energy discharged in the form of the abovementioned spikes of discharges to be distributed uniformly. Advantageously, each of the zones 5a coincides with a hole 3a or 40 of the corresponding grid 3 or 4, (see FIG. 3).

FIG. 3 also shows the plate 2, each of the insulating plates or layers 5 and associated grids 3 and 4 are in contact with each other. The element 5 shown in FIG. 3 is an insulating layer made of a thermoplastics material with a high dielectric constant and low dielectric loss such as polyethylene or polystyrene. The projections 2a of the plate 2 consist of pushed-back or stamped-out portions of small circular cross-section relative to the total area of the plate 2; the stamped-out portions 20 project relative to the median plane of the plate 2 on either side of this median plane.

The combination of the plate 2, dielectric 5 and the grids 3 and 4 represented in FIG. 3 can be manufactured very simply by casting or softening thermoplastics material placed on each of the faces of the plate 2,

the grids 3 and 4 being then applied with a certain pressure onto the thermoplastics material in such a way as to spread the latter over the entire area of the plate 2.

The electric generator 1 shown in FIG. I comprises a step-up transformer 6, the primary winding of which is connected to a source 7 of alternating voltage such as the mains. The generator 1 also comprises means for half-wave rectifying the alternating voltage, which consists, in the case of FIG. 1, of a diode 8 having its anode coupled in series with the secondary winding of the transformer 6 and its cathode coupled to the terminal HT of the generator 1. The other terminal of the secondary winding is connected directly to earth, via a conductor. The diode 8 only allows the positive halfwaves of the alternating high tension voltage provided by the transformer 6 to pass and thus acts as a halfwave rectifier.

The electric generator 1 includes a switch 10 associated with the primary winding of the transformer 6. The switch 10 can be actuated in such a way as to vary the transformation ratio by varying the number of turns of the primary supplied with a constant voltage by the mains 7.

An adjustable, variable resistor 11 is also connected in series with the primary winding of the transformer 6 and makes it possible to adjust with precision the high tension voltage provided by the secondary of the transformer 6.

The device represented in FIG. 1 also possesses means which make it possible to discharge the static electricity collected on the plate 2 and the grids 3 and 4 during the polarization of the latter by the half-wave rectified voltage provided by the generator 1.

These discharge means are interposed between the plate 2 and the grids 3 and 4 and comprises in the present case, a resistor 9 of a few megohms.

In the embodiment illustrated in FIG. 2, the circuit associated with the primary winding of the transformer is identical to that of FIG. 1. However, the transformer 6 comprises two secondary coils 6a wound as a pair in the opposite sense on the same core and having a common terminal 13 connected to earth. The anode of a diode 8 is connected to the other terminal of each secondary coil 60. A series of plate 2/dielectric S/grids 4 combinations, connected in parallel, is thus supplied from the HT terminal of each secondary coil 6a, each HT being connected to the cathode of its associated diode 8. It is possible for each element of these combinations to be identical to that shown in FIG. 3.

The half-wave of the primary alternating current provided by the mains 7, this half-wave being the one removed in the case of FIG. 1, is thus used and as a result of this the heating of the transformer 6 is considerably reduced. Furthermore, as represented in FIG. 2, the device can comprise a cylindrical metal tube 14 which is connected to earth and which acts as a pipeline for the gaseous effluent to be treated. The metal tube 14 surrounds coaxially a central electrode 15 of cylindrical shape which is connected to the terminals HT of the generator 1. A tube 21 made of a dielectric insulating material is placed coaxially inside the tube 14, and the tube 21 is surrounded by a cylindrical grid 16 which is itself connected to a terminal HT of the generator 1 via a resistor 17.

Advantageously, an adjustable resistance 22 is interposed between earth and the grids 3 and 4 of each plate 2/dielectric S/grids 3 and 4 combination.

Thus the device represented in FIG. 2 comprises a plurality ofjuxtaposed elements in the general form of a plate 23, parallel to one another and delimiting between them zones of a treatment space 20 where the gaseous fluid, such as air, to be treated circulates, each element 23 consisting of a plate/dielectric/grids combination.

The device for the treatment of air described above makes it possible to treat the air in a building very economically by only consuming of the order of 3 to 5 watts to treat m to 200 m of air per hour. This device can also treat residual effluents of local concentrations of pollutant gases in streets, crossroads, tunnels and the like.

It is advantageous to draw the air to be treated by means of fans or blowers, so as to create a flow in which one or more devices for the treatment of air would be placed.

I claim:

1. Apparatus for destroying pollutant molecules such as $0 H S, NH CH or of the type C,,H,,, and for increasing the quantity of negative ions contained in a gaseous fluid, comprising:

a. electric generator means for generating unidirectional pulsated current, said generator means having at least one positive pole and a negative pole; and

b. at least one treatment element to be disposed in the gaseous fluid to be treated, the treatment element including (i) a back electrode connected to said positive pole to receive said unidirectional pulsated current, (ii) an insulating layer disposed on one side about said back electrode to insulate electrically at least one face of said back electrode from said gaseous fluid, and ((iii) a front electrode grid connected to said negative pole and covering said insulating layer on the side opposite said one side about said back electrode, said back electrode including a plurality of substantially pin-point projecting zones distributed uniformly over the entire area of at least a side which faces towards said front electrode wherein each zone acts as a point of emission of positive polarity of an electric induction field wherein said back electrode, said insulating layer and said front electrode grid are in contact with each other.

2. Apparatus as claimed in claim 1, wherein said insulating layer comprises a thermoplastics material.

3. Apparatus as claimed in claim 1, wherein said front electrode grid includes holes and wherein said insulating layer is in the form of an insulating plate having zones of small area which are such as to provide a greater capacitance per unit area between opposite faces of the plate than the capacitance per unit area between the faces of the remainder of said insulating plate, said zones being uniformly distributed over said insulating plate and coinciding with the holes in said front electrode grid.

4. Apparatus as claimed in claim 1, wherein said generator means comprises a step-up transformer having a primary winding coupled to a source of alternating voltage and a secondary winding coupled to a rectifier means which is coupled to said positive pole.

5. Apparatus as claimed in claim 1, further comprising a discharge resistor connected between said back electrode and front electrode grid.

6. Apparatus according to claim 1 wherein said insulating layer is a plate.

7. An electric device as claimed in claim 1, wherein said back electrode comprises a continuous metal plate.

8. Apparatus as claimed in claim 7, wherein said front electrode grid includes apertures and each projection of said metal plate coincides with an aperture in said front electrode grid.

9. Apparatus as claimed in claim 7, wherein said continuous metal plate is surrounded by a treatment space and is covered on both its faces by said insulating layer which is itself covered on both sides by a corresponding front electrode grid, said front electrode grids being connected electrically to one another.

10. Apparatus as claimed in claim 9, further comprising projecting zones projecting from both sides of said plate on either side of a median plane of said plate.

11. Apparatus as claimed in claim 1, wherein said front electrode grid is coupled to earth.

12. Apparatus as claimed in claim 11, further comprising an adjustable resistor connected between earth and the front electrode grid.

13. Apparatus as claimed in claim 1, further having a plurality of juxtaposed treatment elements arranged in parallel with one another and delimiting between them a treatment space where the gaseous fluid to be treated circulates.

14. Apparatus as claimed in claim 13, wherein said generator means includes a transformer having two secondary windings wound in phase opposition and which have a common terminal connected to earth, a positive pole connected to each secondary winding and a diode having its anode connected to said positive pole of each secondary winding, and wherein a series of treatment elements is connected in parallel to the positive pole and common terminal of each secondary winding.

15. An electric device for the treatment of a gaseous fluid by setting up a zone with different electric potentials in a treatment space, comprising, in combination:

a. generator means for generating unidirectional pulses of electric current, said generator means including a transformer having two secondary windings wound in phase opposition and which have a common terminal connected to earth, a live output terminal connected to each secondary winding and a diode having its anode connected to said live terminal of each secondary winding; and

b. a plurality of juxtaposed treatment elements arranged in parallel with one another and delimiting between them a treatment space where gaseous fluid to be treated circulates, wherein a series of treatment elements is connected in parallel to said live and common terminals of each secondary winding, said treatment elements including (i) a first electrode connected to said live output terminal to receive said unidirectional pulses of electric current, (ii) a solid dielectric material so disposed about said first electrode as to insulate electrically at least one face of said first electrode from said gaseous fluid, and (iii) a second, grid-like electrode disposed so as to cover at least partially the dielectric material on the side exposed to the gaseous fluid to be treated. 

1. APPARATUS FOR DESTROYING MOLECULES SUCH AS SO2 H2S, NH3, CH4, OR OF THE TYPE CNHP, AND FOR INCREASING THE QUANTITY OF NEGATIVE IONS CONTAINED IN A GASEOUS FLUID, COMPRISING, A. ELECTRIC GENERATOR MEANS FOR GENERATING UNIDIRECTIONAL PULSATED CURRENT, SAID GENERATOR MEANS HAVING AT LAST ONE POSITIVE POLE AND A NEGATIVE POLE, AND B. AT LEAST ONE TREATMENT ELEMENT TO BE DISPOSED IN THE GASEOUS FLUID TO BE TREATED, THE TREATMENT ELEMENT INCLUDING (I) A BACK ELECTRODE CONNECTED TO SAID POSITIVE POLE TO RECEIVE SAID UNIDERECTIONAL PULSATED CURRENT, (II) AN INSULATING LAYER DISPOSED ON ONE SIDE ABOUT SAID BACK ELECTRODE TO INSULATE ELECTRICALLY AT LEAST ONE FACE OF SAID BACK ELECTRODE FROM SAID GASEOUS FLUID, AND ((III) A FRONT ELECTRODE GRID CONNECTED TO SAID NEGATIVE POLE AND CONERIN SAID INSULATING LAYER ON THE SIDE OPPOSITE SIDE ONE SIDE ABOUT SAID BACK ELECTRODE, SAID BACK ELECTRODE INCLUDING A PLURALITY OF SUBSTANTIALLY PIN-POINT PROJECTING ZONES DISTRIBUTED UNIFORMLY OVER THE ENTIRE AREA OF AT LEAST A SIDE WHICH FACES TOWARDS SAID FRONT ELECTRODE WHEREIN EACH ZONE ACTS AS A POINT OF EMISSION OF POSITIVE POLARITY OF AN ELECTRIC INDUCATION FIELD WHEREIN SAID BACK ELECTRODE, SAID INSULATING LAYER AND SAID FRONT ELECTRODE GRID ARE IN CONTACT WITH EACH OTHER.
 2. Apparatus as claimed in claim 1, wherein said insulating layer comprises a thermoplastics material.
 3. Apparatus as claimed in claim 1, wherein said front electrode grid includes holes and wherein said insulating layer is in the form of an insulating plate having zones of small area which are such as to provide a greater capacitance per unit area between opposite faces of the plate than the capacitance per unit area between the faces of the remainder of said insulating plate, said zones being uniformly distributed over said insulating plate and coinciding with the holes in said front electrode grid.
 4. Apparatus as claimed in claim 1, wherein said generator means comprises a step-up transformer having a primary winding coupled to a source of alternating voltage and a secondary winding coupled to a rectifier means which is coupled to said positive pole.
 5. Apparatus as claimed in claim 1, further comprising a discharge resistor connected between said back electrode and front electrode grid.
 6. Apparatus according to claim 1 wherein said insulating layer is a plate.
 7. An electric device as claimed in claim 1, wherein said back electrode comprises a continuous metal plate.
 8. Apparatus as claimed in claim 7, wherein said front electrode grid includes apertures and each projeCtion of said metal plate coincides with an aperture in said front electrode grid.
 9. Apparatus as claimed in claim 7, wherein said continuous metal plate is surrounded by a treatment space and is covered on both its faces by said insulating layer which is itself covered on both sides by a corresponding front electrode grid, said front electrode grids being connected electrically to one another.
 10. Apparatus as claimed in claim 9, further comprising projecting zones projecting from both sides of said plate on either side of a median plane of said plate.
 11. Apparatus as claimed in claim 1, wherein said front electrode grid is coupled to earth.
 12. Apparatus as claimed in claim 11, further comprising an adjustable resistor connected between earth and the front electrode grid.
 13. Apparatus as claimed in claim 1, further having a plurality of juxtaposed treatment elements arranged in parallel with one another and delimiting between them a treatment space where the gaseous fluid to be treated circulates.
 14. Apparatus as claimed in claim 13, wherein said generator means includes a transformer having two secondary windings wound in phase opposition and which have a common terminal connected to earth, a positive pole connected to each secondary winding and a diode having its anode connected to said positive pole of each secondary winding, and wherein a series of treatment elements is connected in parallel to the positive pole and common terminal of each secondary winding.
 15. An electric device for the treatment of a gaseous fluid by setting up a zone with different electric potentials in a treatment space, comprising, in combination: a. generator means for generating unidirectional pulses of electric current, said generator means including a transformer having two secondary windings wound in phase opposition and which have a common terminal connected to earth, a live output terminal connected to each secondary winding and a diode having its anode connected to said live terminal of each secondary winding; and b. a plurality of juxtaposed treatment elements arranged in parallel with one another and delimiting between them a treatment space where gaseous fluid to be treated circulates, wherein a series of treatment elements is connected in parallel to said live and common terminals of each secondary winding, said treatment elements including (i) a first electrode connected to said live output terminal to receive said unidirectional pulses of electric current, (ii) a solid dielectric material so disposed about said first electrode as to insulate electrically at least one face of said first electrode from said gaseous fluid, and (iii) a second, grid-like electrode disposed so as to cover at least partially the dielectric material on the side exposed to the gaseous fluid to be treated. 